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Java example source code file (ExposeFieldsTest.java)

This example Java source code file (ExposeFieldsTest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

classwithexposedfields, classwithinterfacefield, classwithnoexposedfields, exception, expose, exposefieldstest, integer, override, reflection, someinterface, someinterfaceinstancecreator, someobject, string, stringbuilder, testcase

The ExposeFieldsTest.java Java example source code

/*
 * Copyright (C) 2008 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.gson.functional;

import java.lang.reflect.Type;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.InstanceCreator;
import com.google.gson.annotations.Expose;

import junit.framework.TestCase;

/**
 * Unit tests for the regarding functional "@Expose" type tests.
 *
 * @author Joel Leitch
 */
public class ExposeFieldsTest extends TestCase {

  private Gson gson;

  @Override
  protected void setUp() throws Exception {
    super.setUp();
    gson = new GsonBuilder()
        .excludeFieldsWithoutExposeAnnotation()
        .registerTypeAdapter(SomeInterface.class, new SomeInterfaceInstanceCreator())
        .create();
  }

  public void testNullExposeFieldSerialization() throws Exception {
    ClassWithExposedFields object = new ClassWithExposedFields(null, 1);
    String json = gson.toJson(object);

    assertEquals(object.getExpectedJson(), json);
  }

  public void testArrayWithOneNullExposeFieldObjectSerialization() throws Exception {
    ClassWithExposedFields object1 = new ClassWithExposedFields(1, 1);
    ClassWithExposedFields object2 = new ClassWithExposedFields(null, 1);
    ClassWithExposedFields object3 = new ClassWithExposedFields(2, 2);
    ClassWithExposedFields[] objects = { object1, object2, object3 };

    String json = gson.toJson(objects);
    String expected = new StringBuilder()
        .append('[').append(object1.getExpectedJson()).append(',')
        .append(object2.getExpectedJson()).append(',')
        .append(object3.getExpectedJson()).append(']')
        .toString();

    assertEquals(expected, json);
  }

  public void testExposeAnnotationSerialization() throws Exception {
    ClassWithExposedFields target = new ClassWithExposedFields(1, 2);
    assertEquals(target.getExpectedJson(), gson.toJson(target));
  }

  public void testExposeAnnotationDeserialization() throws Exception {
    String json = "{a:3,b:4,d:20.0}";
    ClassWithExposedFields target = gson.fromJson(json, ClassWithExposedFields.class);

    assertEquals(3, (int) target.a);
    assertNull(target.b);
    assertFalse(target.d == 20);
  }

  public void testNoExposedFieldSerialization() throws Exception {
    ClassWithNoExposedFields obj = new ClassWithNoExposedFields();
    String json = gson.toJson(obj);

    assertEquals("{}", json);
  }

  public void testNoExposedFieldDeserialization() throws Exception {
    String json = "{a:4,b:5}";
    ClassWithNoExposedFields obj = gson.fromJson(json, ClassWithNoExposedFields.class);

    assertEquals(0, obj.a);
    assertEquals(1, obj.b);
  }
  
  public void testExposedInterfaceFieldSerialization() throws Exception {
    String expected = "{\"interfaceField\":{}}";
    ClassWithInterfaceField target = new ClassWithInterfaceField(new SomeObject());
    String actual = gson.toJson(target);
    
    assertEquals(expected, actual);
  }
  
  public void testExposedInterfaceFieldDeserialization() throws Exception {
    String json = "{\"interfaceField\":{}}";
    ClassWithInterfaceField obj = gson.fromJson(json, ClassWithInterfaceField.class);

    assertNotNull(obj.interfaceField);
  }

  private static class ClassWithExposedFields {
    @Expose private final Integer a;
    private final Integer b;
    @Expose(serialize = false) final long c;
    @Expose(deserialize = false) final double d;
    @Expose(serialize = false, deserialize = false) final char e;

    public ClassWithExposedFields(Integer a, Integer b) {
      this(a, b, 1L, 2.0, 'a');
    }
    public ClassWithExposedFields(Integer a, Integer b, long c, double d, char e) {
      this.a = a;
      this.b = b;
      this.c = c;
      this.d = d;
      this.e = e;
    }

    public String getExpectedJson() {
      StringBuilder sb = new StringBuilder("{");
      if (a != null) {
        sb.append("\"a\":").append(a).append(",");
      }
      sb.append("\"d\":").append(d);
      sb.append("}");
      return sb.toString();
    }
  }

  private static class ClassWithNoExposedFields {
    private final int a = 0;
    private final int b = 1;
  }
  
  private static interface SomeInterface {
    // Empty interface
  }
  
  private static class SomeObject implements SomeInterface {
    // Do nothing
  }
  
  private static class SomeInterfaceInstanceCreator implements InstanceCreator<SomeInterface> {
    @Override public SomeInterface createInstance(Type type) {
      return new SomeObject();
    }
  }
  
  private static class ClassWithInterfaceField {
    @Expose
    private final SomeInterface interfaceField;

    public ClassWithInterfaceField(SomeInterface interfaceField) {
      this.interfaceField = interfaceField;
    }
  }  
}

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